1. Field of the Invention
The present invention relates to a light source device.
2. Description of the Related Art
In general, there has been developed a light source device which emits light from a small solid-state light source, converts this light by a light converting member, and changes illumination light into a desired irradiation pattern or a desired color. For example, International Publication No. 2008/105527 discloses a light source device which is a combination of an LED chip disposed on a metallic substrate, a sealing resin sealing the LED chip, and a fluorescent material disposed on the sealing resin. In this light source device, a plate-shaped fluorescent material disposed on the LED chip is used to convert the wavelength of part of excitation light emitted from the LED chip and then emit fluorescence. In this way, the technique according to International Publication No. 2008/105527 adjusts the illumination light by the excitation light that has passed through the fluorescent material and by the fluorescence emitted from the fluorescent material.
For example, as shown in International Publication No. 2008/105527, the light source device which adjusts the illumination light by the excitation light that has passed through the fluorescent material and by the fluorescence emitted from the fluorescent material has the following problems. That is, the excitation light passing through the fluorescent material is higher in intensity in the vicinity of an optical axis and lower in intensity at a circumferential edge. In contrast, the fluorescence emitted from the fluorescent material is isotropically scattered, and has an isotropic light intensity. Thus, the illumination light emitted from such a light source device is unevenly colored light having a stronger excitation light component in the center and a weaker fluorescent component at the circumferential edge.